The invention relates generally to network systems such as Local Area Network (LAN) systems and more particularly to techniques and device models to provide high availability interfaces, and systems.
It has been generally known in the network systems field how to provide redundant capabilities. Redundant packet forwarding devices are especially useful to handle the possibility of failed links and/or failed packet forwarding devices (e.g. switches, routers, bridges). However, the detection of network topology loops and the utilization of redundant paths is problematic, particularly in view of the time involved in detecting the path and rerouting traffic. Further, protocols which have been used are complicated to configure and manage.
Traditionally the spanning tree protocol has been use to provide both Layer 1 and 2 redundancy, in switch networks, by configuring alternate paths. When a link or switch element fails, a backup link is activated. The spanning tree algorithm defines the active and backup links in the topology. Spanning tree is designed to control the many switches of the topology and has a slow (in the tens of seconds) reconfiguration time.
Spanning tree has a significant disadvantage as to the reconfiguration time. As network systems become more complex and handle additional traffic, the reconfiguration time becomes increasingly problematic. Further, spanning tree disables the redundant path. This negates the possibility of using redundant paths for increases in throughput.